Lpc2000

Hi,

First, sorry for long mail.

Thanks everybody for reply.

Yes, I know I can address fixed address like:
unsigned int *a = (void * )0x81000000;
*a = 0x11223344;

or 
#define something  (*((volatile unsigned long *) 0x81000000)) 

Ok, I have 2 problems.
I would like to convert my 320x240 GLCD routines to work with
framebuffer, because sed1335 not a fast IC.
I need 2 buffer 9600byte each, in the external space of Lpc2292.
One buffer where I write lines, pix etc, other that store the actual
picture, what is on the GLCD. Then I only copy the CHANGED bytes.
Is this ok?
So, how may I declare and use that 2 9600byte arrays in external ram?

My second problem. Here is a little prog:
unsigned int *a = (void * )0x81000000;

	*a = 0x11223344;
	unsigned int *b = (void * )0x81000004;
	*b = 0x55667788;
	printf("Memory0.4: %x\r\n",*a);
	printf("Memory4.4: %x\r\n",*b);
	unsigned char *ss = (void*)0x81000001;
	printf("Memory1.1: %x\r\n",*ss);
	printf("Memory0.4: %x\r\n",*a);	
	ss = (void*)0x81000002;
	printf("Memory2.1: %x\r\n",*ss);
	ss = (void*)0x81000003;
	printf("Memory3.1: %x\r\n",*ss);
	*ss = 0x99;
	printf("Memory3.1ch: %x\r\n",*ss);
	printf("Memory0.4: %x\r\n",*a);
	ss = (void*)0x81000003;
	*ss = 0x77;
	printf("Memory0.4: %x\r\n",*a);
	ss = (void*)0x81000000;
	*ss = 0x88;
	printf("Memory0.1ch: %x\r\n",*ss);
	printf("Memory0.4: %x\r\n",*a);

And here is the output:

Memory0.4: 11223344
Memory4.4: 55667788
Memory1.1: 33
Memory0.4: 11223344
Memory2.1: 22
Memory3.1: 11
Memory3.1ch: 99
Memory0.4: 99223344
Memory0.4: 77223344
Memory0.1ch: 88
Memory0.4: 77223344

Why can I change the 1-3 byte of a 32bit location, but not the 0.?

Thanks.
Andrew